South Korean President Moon Jae-in and Chinese Premier Li Keqiang agreed Wednesday to continue working together to peacefully denuclearize North Korea, while stressing the need for the international community to offer the impoverished North adequate rewards in return.

"The two leaders agreed that the international community, including the United States, must actively take part in ensuring a bright future for North Korea through a security guarantee and support for its economic development in case North Korea does completely denuclearize, instead of demanding North Korea unconditionally denuclearize," Moon's chief press secretary Yoon Young-chan told reporters.

Moon and Li met on the sidelines of the three-way summit in Tokyo that also involved Japanese Prime Minister Shinzo Abe.

South Korean President Moon Jae-in (R) and Chinese Premier Li Keqiang shake hands before the start of their bilateral talks in Tokyo on May 9, 2018. (Yonhap)

"They also reached an agreement that a rail construction project to link Seoul with (North Korea's) Shinuiju and China may be reviewed to support North Korea's economic development and that a joint feasibility study by South Korea and China may be launched in advance," the official from the South Korean presidential office Cheong Wa Dae said.

Wednesday's talks came about two weeks after Moon and North Korean leader Kim Jong-un agreed to push for the railroad project in their historic bilateral summit at the border truce village of Panmunjom inside the heavily fortified Demilitarized Zone that divides the two Koreas.

In their so-called Panmunjom Declaration, the leaders of the two Koreas also agreed to seek complete denuclearization of the Korean Peninsula and a formal end to the 1950-53 Korean War.

The divided Koreas technically remain at war as the 1950-53 war ended only with an armistice.

The Moon-Li meeting also came after Kim's surprise trip earlier this week to China's Dalian for a meeting with Chinese President Xi Jinping.

Li noted that the North has a firm determination to completely denuclearize and that the country fully understands what it needs to do.

North Korea "is waiting for corresponding feedback from the United States," the Chinese official told Moon, according to Yoon.

U.S. President Donald Trump has agreed to meet with Kim to discuss the North's denuclearization process. He has said the location of the first-ever U.S.-North Korea summit has been set. U.S. Secretary of State Mike Pompeo is currently in Pyongyang, possibly to set an exact date for the summit, a Cheong Wa Dae official said earlier.

Moon asked for China's continued support, especially for the upcoming North Korea-U.S. summit that he earlier said may decide how and when North Korea will give up its nuclear ambitions.

Li said China will closely work with South Korea to further develop the countries' bilateral relationship and pursue complete denuclearization of the Korean Peninsula, according to Cheong Wa Dae pool reports.

"China plans to push for a healthy, safe bilateral relationship with South Korea and push for the process of denuclearizing the Korean Peninsula together with South Korea," he said.